function y = Diagonal_5(x)
%  Diagonal5 Function  (MatrixRom)
%x0=[1.1,1.1, ...,1.1]  
%fmin=n/2
%Author:shi yangyang
n=length(x);
y=ones(1,n);
for i=1:1:n
    y(i)=log(exp(x(i))+exp(-x(i)));
end
y=sum(y);